2015 Annual FWP Madison River Report

Every Year since 1990, Montana FWP has received funding from dam operators to complete a fisheries study on the Madison River Drainage. Recently, in December, the 2015 Annual Report was completed. These studies report on the effects of hydropower operations at both Hebgen and Ennis dams on all fisheries. This includes basic populations parameters of Rainbow and Brown Trout populations in the Madison, information on monitoring efforts of recent (2014) introduction attempts for native Arctic Grayling, and conservation of Westslope Cutthroat Trout in the Madison River drainage.

These annual reports, though chock full of important graphs and numbers, are still about as exciting to read as a Master’s Thesis (I’ve written one), and are about as easy to digest as a well done moose round steak (I’ve had one…the result of a neglected grill). Neither of which were very much fun, so we’ll break down some of the more pertinent population highlights for anglers on the Madison here. The Report traditionally has monitored parameters on fisheries in three distinct sections: Norris, Varney, and Pine Butte. So, here you are!

Arctic Grayling Update:

Three young-of-the-year grayling were captured in Fall monitoring, one in the West Fork Madison Spring and two in Moore’s Creek.

Eggs were placed in both O’Dell and Lake Creeks during May.

No juvenile Arctic Grayling were captured in Ennis Lake during beach seining.

In recent years rainbow trout in the 12 inches and larger group have trended upward in population estimates in all three river sections. This trend continued in 2015 for Norris and Varney sections. There was a decrease in 2015 in the number of rainbows in those size classes in the Pine Butte section. Details on population parameters per section:

Pine Butte Section:

6” or larger: ~1900 per river mile

12” or larger: ~900 per river mile

14” or larger: ~600 per river mile

15” or larger: ~400 per river mile

Varney Section

6” or larger: ~1800 per river mile

12” or larger: ~400 per river mile

16” or larger: ~100 per river mile

Norris Section:

6” or larger: ~2200 per river mile

12” or larger: ~1200 per river mile

Ennis Lake Gillnet Survey:

Avg. Length: ~14” (Up from 2014 – 12”)

Num. Captured: ~55 (Down from 2014 – 91)

Brown Trout Update

Brown trout in the Pine Butte section remain at historically high levels, remaining at or near 2014 levels, while in the Norris section their numbers continue to decrease. Details on population parameters per section:

Pine Butte Section:

6” or larger: ~2600 per river mile

12” or larger: ~1200 per river mile

15” or larger: ~700 per river mile

Varney Section

6” or larger: ~1100 per river mile

12” or larger: ~400 per river mile

15” or Larger: ~250 per river mile

18” or larger: ~150 per river mile

Norris Section:

6” or larger: ~1000 per river mile

12” or larger: ~500 per river mile

Ennis Lake Gillnet Survey:

Avg. Length: ~16” (Up from 2014 – 14”)

Num. Captured: ~23 (Down from 2014 – 41)

General Flow Information

Water temperature monitoring sites from Hebgen Dam (Hebgen discharge) to McAtee have been monitored since 1995, and have shown their highest maximum temperatures in 2012 – 2015.